feat: application icon family (a meshed bracket) drawn with VectorCraft (#37)

cargo xtask app-icon computes an isometric L bracket with a bolt hole and a
structured hexahedral mesh (O-grid around the hole), draws it with
vectorcraft-cli and writes icon.svg/png, small-size artwork, the iconset,
icns, ico, an Icon Composer ModelCraft.icon (floor grid Default/Dark, part,
mesh) and its actool Assets.car. The desktop app uses the 256 px export as
its window icon, falling back to eframe's default if it cannot be decoded.


Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

xtask/src/assets.rs

@@ -10,6 +10,7 @@ const ASSET_EXT: &[&str] = &[
     "svg",
     "ico",
     "icns",
+    "car",
     "ttf",
     "otf",
     "woff",